Method for segmenting and reassembling packet based on tree structure, and method for transmitting/receiving packet using the same

Abstract

Provided is a method of segmenting a packet using a tree structure in order to reduce headers in the packet when the packet is transmitted or received in a wireless communication system using an adaptive modulation and coding (AMC), and a method of transmitting/receiving a packet using the same. The method includes the steps of: determining whether a transmitting processing data unit (PDU) is a retransmitted PDU; determining whether a size of the retransmitted PDU is a transmittable size allowed by a corresponding adaptive modulation and coding (AMC) option if the transmitting PDU is the retransmitted PDU; and segmenting the retransmitting PDU, inserting a header and a sub header with identification information for reassembling into each of the segmented PDUs and transmitting the segmented PDUs.

1. A method of segmenting a packet into a plurality of processing data units (PDUs) at a transmitting side of a wireless communication system and transmitting the PDUs to a receiving side of the wireless communication system, while an environment of a channel of the transmission varies from time to time, the method comprising:
 selecting each of the plurality of PDUs and performing steps (a)-(e): 
 (a) determining whether the selected PDU is a retransmitted PDU; 
 (b) if the selected PDU is not a retransmitted PDU, transmitting the selected PDU from the transmitting side using the channel of the wireless communication system; 
 (c) if the selected PDU is a retransmitted PDU, determining whether the selected PDU has a transmittable size allowed by a corresponding adaptive modulation and coding (AMC) option of the wireless communication system, representing the retransmitted PDU as a root node of a tree; 
 (d) if the selected PDU has a transmittable size, transmitting the selected PDU from the transmitting side using the channel of the wireless communication system; and 
 (e) if the selected PDU does not have a transmittable size,
 segmenting the selected PDU into segmented PDUs, 
 representing the selected PDU as a parent node of the tree, and each of the segmented PDUs as a child node of the tree, 
 inserting a header and a sub header with identification information for reassembling into each of the segmented PDUs, the identification information corresponding to a depth of the child node, and, 
 selecting each of the segmented PDUs and treating the selected segmented PDU as a selected PDU to repeat steps (c) to (e) 
 
 wherein
 the segmenting in step (e) includes partitioning the selected PDU into a first segmented PDU and a second segmented PDU, 
 first identification information of the first segmented PDU is a first sub sequence number (SSN) defined by: SSN 1stPDU =P+1, 
 second identification information of the second segmented PDU is a second SSN defined by: SSN 2ndPDU =P+2 (L−D−1) , 
 P denotes a sub sequence number before the partitioning, 
 L is a bit length of the identification information, and 
 D is a depth of a node corresponding to a respective one of the first and second segmented PDUs. 
 
 
     
     
       2. The method as recited in  claim 1 , wherein the header includes information denoting whether the sub header is inserted or not. 
     
     
       3. The method of  claim 1 , further comprising the step of inserting parameters related to retransmission in the sub header for a retransmission of the selected PDU. 
     
     
       4. A method of reassembling a packet in a wireless communication system, the packet being segmented at a transmitting side of the wireless communication system into a plurality of processing data units (PDUs), which are transmitted to and received at a receiving side of the wireless communication system through a transmission channel having an environment varied from time to time, each PDU having a same sequence number (SN) and a sub sequence number (SSN), the receiving side having a receiving buffer, the method comprising the steps of:
 determining at the receiving side of the wireless communication system whether one of the received PDUs is a retransmitted PDU; and 
 if the one PDU is a retransmitted PDU,
 finding, from the receiving buffer, PDUs having the same SN as the one PDU; 
 representing the found PDUs using a tree, each found PDU being a node of the tree, the SSN of each found PDU corresponding to a depth of the node; 
 choosing one of the found PDUs that has a specific SSN that is smaller than and closest to the SSN of the one PDU; and 
 inserting the one PDU after the chosen PDU to reassemble the one PDU and the chosen PDU, wherein 
 the tree is a full binary tree; 
 the found PDUs including a first PDU having a first SSN and a second PDU having a second SSN, the second SSN being larger than and closest to the first SSN in the tree, the first PDU having a parent PDU with a parent SSN; 
 if the first PDU is a first child of the parent PDU, the second SSN is defined by: P+2 L−D −1+X(0≦X≦D), wherein P denotes the first SSN, L denotes a length of bits for representing a SSN identification, D is a depth of a node representing the first PDU, and X is an integer, and 
 if the first PDU is a second child of the parent PDU, the second SSN is defined by: P′+2 L−D′ −1+X(0≦X≦D), wherein P′ denotes the parent SSN, D denotes a depth of a node representing the parent PDU, and X is an integer.